I still don't like Excel (read this for more info). But apparently I did something wrong when plotting my graph. When entering the 'chart wizard' you should choose 'XY (Scatter)' and not 'Line' (even if you want a line through your points, don't pick the 'Line' option!!). In the wizard you can then choose to draw a line through the points and the graph turns out to be alright. So when would you want to use the 'Line' option? Seriously: I don't know. I cannot find any use for this (unless you try to skew the graph to your advantage, much appreciated by business people, I suspect) so don't pick it. Never. Or use Graph 4.3, Which is a really competent little program and it's free!